To understand the significance of this remarkable distribution it is necessary to examine the geologic strata of Tertiary times, from which it transpires that in those bygone days,. between two and three million years ago, alligators inhabited not only Asia, but Europe as well, even the British Isles—which were not islands then—having their representatives. It is believed that the whole group of crocodiles and alligators originate ed in Eurasia, as the two continents may jointly be called, and that the Yangtze alligator is all that is left lin the Old World of the sub-group which also contains the South American caimans, near relatives of the alligators.
All the other Old World representatives of the Crocodilida: must be classified either as true crocodiles or as gharials, the long-snouted, fish-eating members of the family.
It is from just such peculiar distributions of animals, past and present, that the land formation of bygone ages may be learned, and, in this case, the inference to be drawn is that in Tertiary times Asia and North America were connected by a broad land bridge, which extended sufficiently far south to allow such warmth-loving reptiles as the alligators to spread from one continent to the other.
DirrereNces FROM THE CRoOcoDILE.
One frequently hears the question asked, What is the difference between a "crocodile and an alligaitor? Apart from certain differences in the skull, which need not be discussed here, the chief difference between these two members of the family is that in the alligator the fourth tooth from the front in the lower jaw fits into a pit in the upper jaw, whereas in the crocodile the same tooth fits into a notch, and is visible from the exterior of the animal's head. Another difference is that the alligators have much broader snouts.
The caimans of South America closely resemble the alligators in these characteristics, but they may be distinguished by certain cranial differences.
The gharials are very different from either crocodiles or alligators, since they have very long and slender jaws and snouts, which are armed with numerous and regular teeth. They feed mainly upon fish, but some of the larger specimens are suspected of cating human flesh. They are to be found in the waters of India and Africa.
The chief distinguishing characteristic of the Yangtze alligator appears to be its small size, and this is to be explained by the fact that it represents the last of a once numerous group of reptiles in Asia. But upon this point there is need of more data, for there seems to be no information available as to the size attained by this species. Up to the present the recently caught specimen appears to be the largest taken, its total length being about six fect. Usually specimens that make their appearance in these parts measure from three to four fect. It would be interesting to know of any other large specimens that have been seen and measured by Europeans.
Text read from the printed page and cleaned; old type leaves the occasional error.